This invention relates to slotless and toothless wound stators for electrical machines, and in particular for brushless DC motors which are small fractional or integral horsepower motors that obtain switching by electronic means and shaft position sensing rather than by commutation via brushes.
DC brushless motors conventionally have an outer stator surrounding an inner rotor, the stator containing inwardly directed teeth and slots circumferentially spaced around its inner periphery and extending lengthwise from one end of the stator to the other end. Electrical windings are positioned by various means in the slots between the teeth from end to end of the stator and around the teeth at the opposite ends of the stator. Various disadvantages of such a known configuration include the magnetic discontinuities presented by the slots and teeth, speed limitations due to electronic switching delays occasioned by the presence of the teeth and slots, excessive noise, excessive heat due to switching delays, etc.
Other forms of DC brushless motors are known which eliminate stator teeth and slots, but which variously require specialized coil forms, specialized winding machines to provide coils of special geometry, and/or specialized support means anchored directly onto or into the stator wall to hold the windings. Such structures are expensive and complicated to manufacture.